This invention relates to a micro controller and more particularly to micro controllers that are used where security is necessary such as in IC cards and data banks.
In conventional micro controllers, program security was disregarded and the micro controller was operated directly from the program stored in the memory.
In this kind of micro controller, the program stored in memory could easily be decoded or altered and so when used with IC cards or data banks that require a high level of security, maintaining security was not adequate.